How to match this specific string in RE? - php

Question

Once again I'm stuck at regular expression. There is nowhere any good material where to learn the more advance usage.
I'm trying to match [image width="740" height="249" parameters=""]51lca7dn56.jpg[/image] to $cache->image_tag("$4", $1, $2, "$3").
Everything works great if all the [image] parameters are there, but I need it to match, even if something is missing. So for example [image width="740"]51lca7dn56.jpg[/image].
Current code is:
$text = preg_replace('#\[image width=\"(.*?)\" height=\"(.*?)\" parameters=\"(.*?)\"\](.*?)\[/image\]#e', '$cache->image_tag("$4", $1, $2, "$3")', $text);
Regular expression is the only thing that always gets me stuck, so if anybody could also refer some good resource, so I could manage these types of issues myself, it would be much appreciated.
My dummy version what I'm trying to do is this:
// match only [image]
$text = preg_replace('#\[image\](.*?)\[/image\]#si', '$cache->image_tag("$1", 0, 0, "")', $text);
// match only width
$text = preg_replace('#\[image width=\"(.*?)\"\](.*?)\[/image\]#si', '$cache->image_tag("$2", $1, 0, "")', $text);
// match only width and height
$text = preg_replace('#\[image width=\"(.*?)\" height=\"(.*?)\"\](.*?)\[/image\]#si', '$cache->image_tag("$3", $1, $2, "")', $text);
// match only all
$text = preg_replace('#\[image width=\"(.*?)\" height=\"(.*?)\" parameters=\"(.*?)\"\](.*?)\[/image\]#si', '$cache->image_tag("$4", $1, $2, $3)', $text);
(This code actually doesn't work as expected, but you will understand my point more better.) I hope to put all this horrible mess into one RE call basically.
Final code tested and working based on Ωmega's answer:
// Match: [image width="740" height="249" parameters="bw"]51lca7dn56.jpg[/image]
$text = preg_replace('#\[image\b(?=(?:[^\]]*\bwidth="(\d+)"|))(?=(?:[^\]]*\bheight="(\d+)"|))(?=(?:[^\]]*\bparameters="([^"]+)"|))[^\]]*\]([^\[]*)\[\/image\]#si', '$cache->image_tag("$4", $1, $2, "$3")', $text); // the end is #si, so it would be eaiser to debug, in reality its #e
However, since if width or height might not be there, it will return empty not NULL. So I adopted drews idea of preg_replace_callback():
$text = preg_replace_callback('#\[image\b(?=(?:[^\]]*\bwidth="(\d+)"|))(?=(?:[^\]]*\bheight="(\d+)"|))(?=(?:[^\]]*\bparameters="([^"]+)"|))[^\]]*\]([^\[]*)\[\/image\]#', create_function(
'$matches',
'global $cache; return $cache->image_tag($matches[4], ($matches[1] ? $matches[1] : 0), ($matches[2] ? $matches[2] : 0), $matches[3]);'), $text);

Answer 1

Maybe try a regex like this instead which tries to grab extra params in the image tag (if any). This way, the parameters can be in any order with any combination of included and omitted parameters:
$string = 'this is some code and it has bbcode in it like [image width="740" height="249" parameters=""]51lca7dn56.jpg[/image] for example.';
if (preg_match('/\[image([^\]]*)\](.*?)\[\/image\]/i', $string, $match)) {
var_dump($match);
}
Resulting match:
array(3) {
[0]=>
string(68) "[image width="740" height="249" parameters=""]51lca7dn56.jpg[/image]"
[1]=>
string(39) " width="740" height="249" parameters="""
[2]=>
string(14) "51lca7dn56.jpg"
}
So you can then examine $match[1] and parse out the parameters. You may need to use preg_replace_callback to implement the logic inside the callback.
Hope that helps.

Answer 2

I would suggest you to use regex
\[image\b(?=(?:[^\]]*\bwidth="(\d+)"|))(?=(?:[^\]]*\bheight="(\d+)"|))(?=(?:[^\]]*\bparameters="([^"]+)"|))[^\]]*\]([^\[]*)\[\/image\]
Edit:
$string = 'this is some code and it has bbcode in it like [image width="740" height="249" parameters=""]51lca7dn56.jpg[/image] for example and [image parameters="" height="123" width="456"]12345.jpg[/image].';
if (preg_match_all('/\[image\b(?=(?:[^\]]*\bwidth="(\d+)"|))(?=(?:[^\]]*\bheight="(\d+)"|))(?=(?:[^\]]*\bparameters="([^"]+)"|))[^\]]*\]([^\[]*)\[\/image\]/i', $string, $match) > 0) {
var_dump($match);
}
Output:
array(5) {
[0]=>
array(2) {
[0]=>
string(68) "[image width="740" height="249" parameters=""]51lca7dn56.jpg[/image]"
[1]=>
string(63) "[image parameters="" height="123" width="456"]12345.jpg[/image]"
}
[1]=>
array(2) {
[0]=>
string(3) "740"
[1]=>
string(3) "456"
}
[2]=>
array(2) {
[0]=>
string(3) "249"
[1]=>
string(3) "123"
}
[3]=>
array(2) {
[0]=>
string(0) ""
[1]=>
string(0) ""
}
[4]=>
array(2) {
[0]=>
string(14) "51lca7dn56.jpg"
[1]=>
string(9) "12345.jpg"
}
}